2009 Programme

19 May 2009 – Technical Visit
Stoke-on-Trent, UK

On 19th May the Society held a successful technical visit to Marston’s Brewery at Burton on Trent with participants from as far away as Newcastle and Oxfordshire. Marston’s is one of the largest UK owned brewing companies comprising the Wolverhampton and Dudley, Marston’s, Wychwood, Jennings and Ringwood breweries each with their own distinctive bands.

Brewing for a process engineer is a complex series of unit operations including extraction, evaporation and fermentation with filtration and separation playing a key role at each stage, including the mashing process, the removal of spent hops and trub removal from the wort, as well as yeast from the beer after fermentation. Unlike most industries the most important product characteristic, the flavour profile of the final product, is dependent upon the raw materials and each of the above processes.

We were welcomed with a talk describing the brewing process employed at Marston’s before the tour itself, including the new and old brew houses and the high speed bottling line, but for the writer the highlight of the tour was the fermentation hall to see the unique ‘Burton Union’ system in action. For those of us of a certain age, this is the technique used traditionally for the production of draft Bass, which is still brewed under licence by Marston’s using the same fermentation process today.

Post fermentation the yeast content prior to conditioning is controlled by a centrifuge, and prior to bottling a plate and frame filter removes yeast and protein to ensure that a bright beer results. The final phase of the visit involved tasting of the various products to help us understand how the differences in the ingredients and processing techniques impacted upon the look, aroma and taste of a variety of products brewed, which proved to be as educational as it was enjoyable.

Filter media – a $25 million business. Given the size of the market, it was not surprising that the Filter Media conference and exhibition continues to be one of the most popular events in the diary of The Filtration Society.

The event was introduced by Ken Southerland of Northdoe, who reviewed not only the overall size of the market but the breakdown country by country and the market share of the various media types. Data up to 2008 showed that membranes were by far the biggest component occupying an impressive 36% of the market, more than twice that of second place Spun Melt media at 14%.

The USA continues to dominate the market place having almost a quarter share. A significant development, and perhaps not surprisingly, is that China has now overtaken Japan into second place, but their market share is still only half that of the USA. For all those involved in the filtration business, it was comforting to hear that the market is expected to grow slightly in 2010 but then accelerate from 2011 to 2013.

In a fascinating talk by Mike Vinson of Camfil Farr, the selection and testing of HEPA filters was discussed with respect to regulatory requirements. This was a most appropriate lecture in that it was shown that, by careful selection of the filter media, pleating and configuration it had been possible to reduce the fan motor size on a particular plant without reducing output. The consequential energy saving for one customer alone was over £2 million a year with a reduced annual carbon footprint of almost 8 tons of CO2.

The theme of energy efficient filtration was extended by Thomas Caesar of Freudenberg Filtration Technologies who introduced his lecture with the startling statistic that a third of all energy produced is consumed in filtration processes. Ranking filters in terms of their key energy performance (kep number), which relates pressure drop and the average collection efficiency for 0.4 micron particles, is therefore a convenient and quick way of comparing filters.

One of the problems of filtering in the sub-micron region, especially in liquid systems is flow rate and back pressure. Porvair described a novel system whereby isostatic pressing is used to deposit a 100 micron thick porous metal membrane on a substrate carrier. The resultant structure has significant advantages over other filters in the 0.3 – 3 micron range.

Striking the right balance between high porosity and efficient particle capture is always a difficult challenge, especially if high temperature performance is thrown into the mix. The solution presented by Bekaert was to form ultra-fine wires (down to 1.5 microns) into non-woven mats where porosities of over 80% are achievable for filter ratings down to 3 microns.

Filter efficiency per se is often a rather nebulous concept unless it is clearly defined. For example the percentage weight capture of a dust after a single pass through a filter gives little information on the total costs incurred over the lifetime of an actual filter system. An excellent paper from Hollingsworth and Vose quantified the critical parameters in media performance via the gamma values and projected the savings that could be made on a filter over a lifetime of 5 years.

The final paper of the day from Europlasma NV illustrated how innovative low pressure plasma coatings for filter media can modify the surface characteristics and hence save money through improved efficiencies. Examples included hydrophobic/oleophobic coatings for polypropylene filters.

An extremely valuable part of the conference was a 5 minute poster session where all the exhibitors introduced their products. This saved a lot of time for delegates who were not sure of the relevance of some of the technologies in their particular section of the market.”